Thermographic nondestructive testing methods are known and are used to create images of a sample's subsurface features in order to detect internal flaws or features, measure a sample's thickness, thermal diffusivity, or other characteristics of subsurface features (such as depth and/or lateral size of subsurface features). However, existing techniques do not allow robust automated segmentation of subsurface defects from a data sequence without a prior knowledge of the thermophysical properties of the sample, visual interpretation by an operator, or comparison to a known defect-free sample.